A robot (100) has a robot mechanism unit (1) having a sensor (10) and a control unit (2), and the control unit (2) includes a normal control unit (4) that controls the operation of the robot mechanism unit, and a learning control unit (3) that, when the robot mechanism unit (1) is operated by a speed command that is given by multiplying a teaching speed designated in a task program by a speed change ratio, performs learning to calculate, from a detection result by the sensor (10), a learning correction amount for making the trajectory or position of the control target in the robot mechanism unit (1) approach the target trajectory or target position, or for reducing the vibration of the control target, and performs processes so that the control target position of the robot mechanism unit (1) moves along a fixed trajectory regardless of the speed change ratio.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A robot comprising a robot mechanism unit that has a sensor in a part that is subject to position control, and a control unit that controls an operation of the robot mechanism unit, wherein the control unit comprises: a normal control unit that controls the operation of the robot mechanism unit; a learning control unit that, when the robot mechanism unit is operated by a speed command given by multiplying a teaching speed designated in a task program by a speed change ratio, calculates, from a result detected by the sensor, a learning correction amount configured to make a trajectory or position of a control target of the robot mechanism unit approach a target trajectory or target position that is assigned to the normal control unit, or a learning correction amount configured to reduce a vibration of the control target that is produced when the robot mechanism unit is operated; and a teaching control unit configured to teach or correct a position or speed in the task program, and performs processes so that a control target position of the robot mechanism unit moves on a fixed trajectory regardless of the speed change ratio, wherein the normal control unit operates the robot mechanism unit by a position command that is based on the teaching position set in the task program, the learning correction amount that is calculated by the learning control unit, and the speed command that is given by multiplying the teaching speed set in the task program by the speed change ratio that is used upon calculation of the learning correction amount, and, after the learning correction amount is calculated by the learning control unit, when the position of a teaching point is corrected by the teaching control unit, if a distance between the position of the teaching point after the position correction and the position of the teaching point before the position correction is equal to or greater than a predetermined distance, controls move to the teaching point at the teaching speed, and, if the distance is less than the predetermined threshold, controls the move to the teaching point by the speed command.
2. The robot as claimed in claim 1 , wherein the learning control unit executes learning to calculate the learning correction amount while changing the speed change ratio over a plurality of times until reaching a predetermined maximum speed change ratio.
3. The robot as claimed in claim 2 , wherein the predetermined maximum speed change ratio is calculated by the learning control unit, based on data acquired when the robot mechanism unit is operated, a maximum speed and maximum acceleration that can be tolerated in the robot mechanism unit, or a duration of life of a decelerator.
4. The robot as claimed in claim 2 , wherein the predetermined speed change ratio is set in the control unit from outside.
5. The robot as claimed in claim 1 , wherein, after the learning correction amount is calculated by the learning control unit, when the position of the teaching point is corrected by the teaching control unit, if the distance between the position of the teaching point after the position correction and the position of the teaching point before the position correction is equal to or greater than the predetermined distance, the normal control unit controls the move to the teaching point and move from the teaching point to a next teaching point at the teaching speed, and, if the distance is less than the predetermined threshold, controls the move to the teaching point and the move from the teaching point to the next teaching point by the speed command.
6. The robot as claimed in claim 1 , wherein, after the learning correction amount is calculated by the learning control unit, when the speed command is corrected by the teaching control unit, if a difference between the speed command after the correction and the speed command before the correction is equal to or greater than a predetermined rate or a predetermined value, the normal control unit controls the move to the teaching point at the teaching speed, and, if the difference is lower than the predetermined rate or the predetermined value, controls the move to the teaching point by the speed command.
7. The robot as claimed in claim 1 , wherein the learning control unit comprises a filter for calculating a position vibration component of the robot mechanism unit from data detected by the sensor.
8. The robot as claimed in claim 7 , wherein the learning control unit calculates a position on each axis including the position vibration component by inverse-transforming the data detected by the sensor into three basic axes of each axis of the robot.
9. The robot as claimed in claim 1 , wherein the learning control unit makes the robot mechanism unit execute a predetermined operation, and calculates a position and inclination of the sensor.
10. The robot as claimed in claim 1 , wherein the learning control unit further comprises a memory for storing the learning correction amount.
11. The robot as claimed in claim 1 , wherein the sensor is one of a vision sensor, an acceleration sensor, a gyro sensor, an inertial sensor, an optical sensor and a distortion gauge.
12. The robot as claimed in claim 1 , wherein the sensor comprises a mounting section that can be attached to and detached from the robot mechanism unit.
13. The robot as claimed in claim 12 , wherein the sensor comprises a magnet as the mounting section.
14. A spot welding robot comprising: a robot mechanism unit that comprises a control target part that is subject to position control and a sensor that is mounted on the control target part; a normal control unit that acquires position command data related to a target trajectory or target position of the control target part, and, according to position error data that is calculated using the position command data, operates the robot mechanism unit at a predetermined operation speed, by a task program; and a learning control unit that calculates a trajectory or position of the control target part from a detection result of the sensor, and, by learning control, calculates a learning correction amount, configured to correct a trajectory error between the trajectory and the target trajectory or a position error between the position and the target position, or reduce a vibration of the control target part that is produced when the robot mechanism unit is operated, wherein: the normal control unit corrects the position error data using the learning correction amount; and the learning control unit, in a course of calculating the learning correction amount, calculates maximum speed overrides based on maximum acceleration and maximum speed, respectively, that can be tolerated in the robot mechanism unit by operating the robot mechanism unit, and calculates a maximum operation speed that can be set in the robot mechanism unit based on the minimum value among the calculated maximum speed overrides, and calculates the learning correction amount while increasing the operation speed in one time or over a plurality of times until reaching the maximum operation speed.
15. The spot welding robot as defined in claim 14 , wherein: the normal control unit acquires a target operation speed, which is a target value of the operation speed of the robot mechanism unit; and the learning control unit compares the target operation speed and the maximum operation speed, and, when the target operation speed is less than the maximum operation speed, calculates the learning correction amount while increasing the operation speed in one time or a plurality of times until reaching the target operation speed.
16. The spot welding robot as defined in claim 14 , wherein the learning control unit calculates the maximum operation speed based on a maximum speed and maximum acceleration that can be tolerated in the robot mechanism unit.
17. The spot welding robot as defined in claim 14 , wherein the learning control unit calculates data on each axis by transforming data that is calculated from the detection result of the sensor and that includes the trajectory error, the position error or a vibration component of the control target part, into position coordinates based on each axis of the robot mechanism unit.
18. The spot welding robot as defined in claim 14 , wherein the learning control unit makes the robot mechanism unit execute a predetermined operation and calculates a position and inclination of the sensor.
19. The spot welding robot as defined in claim 14 , further comprising a storage unit for storing the learning correction amount.
20. The spot welding robot as defined in claim 14 , wherein the sensor is one of a vision sensor, an acceleration sensor, a gyro sensor, an inertial sensor and a distortion gauge.
21. The spot welding robot as defined in claim 14 , further comprising a mounting section that allows the sensor to be attached to and detached from the robot mechanism unit.
22. A spot welding robot comprising: a robot mechanism unit that comprises a control target part that is subject to position control and a sensor that is mounted on the control target part; a normal control unit that acquires position command data related to a target trajectory or target position of the control target part, and, according to position error data that is calculated using the position command data, operates the robot mechanism unit at a predetermined operation speed, by a task program; and a learning control unit that calculates a trajectory or position of the control target part from a detection result of the sensor, and, by learning control, calculates a learning correction amount, configured to correct a trajectory error between the trajectory and the target trajectory or a position error between the position and the target position, or reduce a vibration of the control target part that is produced when the robot mechanism unit is operated, wherein: the normal control unit corrects the position error data using the learning correction amount; and the learning control unit performs a process of calculating the learning correction amount and comparing the trajectory error or the position error, or the vibration, with each threshold that is set in advance, and repeats the process, while increasing the operation speed, until the trajectory error or the position error, or the vibration, exceeds each threshold, and increases the operation speed by repeating process of increasing a predetermined amount of override, as long as the trajectory error or the position error, or the vibration, stays within each threshold in a predetermined period before the end of the operation period.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
May 11, 2012
November 11, 2014
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